Abstract Global interest in plant-derived proteins continues to expand, largely due to increasing demand for sustainable and alternative nutritional sources. Within this framework, stinging nettle ( Urtica dioica L.), a relatively underexploited leafy material with notable protein content, offers considerable potential as a novel protein source. This study evaluated the effects of three extraction approaches, alkaline extraction coupled with isoelectric precipitation (AE-IP), ultrasound-assisted extraction (UAE), and ultrafiltration (UF), on the structural, physicochemical, and techno-functional properties of nettle protein concentrates (NPCs). UAE resulted in the greatest protein recovery (41.62%), followed by AE-IP (33.90%) and UF (23.45%), corresponding to approximate yields of 41.62 g, 33.90 g, and 23.45 g of protein concentrate per 100 g of nettle leaf powder, respectively. From a functional perspective, both UF and UAE samples demonstrated higher solubility at alkaline pH (9.0), with values of 90.43% and 82.01%, respectively, compared to 69.24% for AE-IP. These samples also showed improved emulsifying and foaming properties. Microstructural analysis revealed that UF-NPC possessed a more open and less compact morphology with increased interstitial spacing, consistent with its smaller particle size and enhanced water holding capacity. Furthermore, in vitro digestion results indicated that UF-NPC achieved the highest degree of hydrolysis (42.68%) and protein solubility (97.86%), followed by UAE (38.79% and 89.76%) and AE-IP (31.03% and 76.35%). Overall, the results highlight ultrasound-assisted extraction and ultrafiltration as promising techniques for generating nettle protein concentrates with improved functional performance, reinforcing the potential of nettle as a sustainable ingredient for future food applications.
Tanyitiku et al. (Wed,) studied this question.